--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/contrib/analyze_brprob	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,146 @@
+#!/usr/bin/awk -f
+# Script to analyze experimental results of our branch prediction heuristics
+# Contributed by Jan Hubicka, SuSE Inc.
+# Copyright (C) 2001, 2003 Free Software Foundation, Inc.
+#
+# This file is part of GCC.
+#
+# GCC is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GCC is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING.  If not, write to
+# the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+# Boston, MA 02110-1301, USA.
+#
+#
+# This script is used to calculate two basic properties of the branch prediction
+# heuristics - coverage and hitrate.  Coverage is number of executions of a given
+# branch matched by the heuristics and hitrate is probability that once branch is
+# predicted as taken it is really taken.
+#
+# These values are useful to determine the quality of given heuristics.  Hitrate
+# may be directly used in predict.c.
+#
+# Usage:
+#  Step 1: Compile and profile your program.  You need to use -fprofile-arcs
+#    flag to get the profiles
+#  Step 2: Generate log files.  The information about given heuristics are
+#    saved into *.bp dumps.  You need to pass the -db switch to the compiler as well
+#    as -fbranch-probabilities to get the results of profiling noted in the dumps.
+#    Ensure that there are no "Arc profiling: some edge counts were bad." warnings.
+#  Step 3: Run this script to concatenate all *.life files:
+#    analyze_brprob `find . -name *.life`
+#    the information is collected and print once all files are parsed.  This
+#    may take a while.
+#    Note that the script does use bc to perform long arithmetic.
+#  Step 4: Read the results.  Basically the following table is printed:
+#  (this is just an example from a very early stage of branch prediction pass
+#   development, so please don't take these numbers seriously)
+#
+#HEURISTICS                  BRANCHES  (REL)  HITRATE             COVERAGE  (REL)
+#opcode                          2889  83.7%  94.96%/ 97.62%      7516383  75.3%
+#pointer                          246   7.1%  99.69%/ 99.86%       118791   1.2%
+#loop header                      449  13.0%  98.32%/ 99.07%        43553   0.4%
+#first match                     3450 100.0%  89.92%/ 97.27%      9979782 100.0%
+#loop exit                        924  26.8%  88.95%/ 95.58%      9026266  90.4%
+#error return                     150   4.3%  64.48%/ 86.81%       453542   4.5%
+#call                             803  23.3%  51.66%/ 98.61%      3614037  36.2%
+#loop branch                       51   1.5%  99.26%/ 99.27%        26854   0.3%
+#noreturn call                    951  27.6% 100.00%/100.00%      1759809  17.6%
+#
+#  The heuristic called "first match" is a heuristic used by GCC branch
+#  prediction pass and it predicts 89.92% branches correctly.
+#
+#  The quality of heuristics can be rated using both, coverage and hitrate
+#  parameters.  For example "loop branch" heuristics (predicting loopback edge
+#  as taken) have both very high hitrate and coverage, so it is very useful.
+#  On the other hand, "exit block" heuristics (predicting exit edges as not
+#  taken) have good hitrate, but poor coverage, so only 3 branches have been
+#  predicted.  The "loop header" heuristic has problems, since it tends to
+#  misspredict.
+#
+#  The implementation of this script is somewhat brute force.  My awk skills
+#  are limited.
+
+function longeval(e)
+{
+  e = "echo \"scale = 2 ;"e"\" | bc"
+  e | getline res
+  close (e)
+  return res
+}
+
+BEGIN {nnames = 0}
+
+/^  .* heuristics: .*.$/ {
+    name=$0
+    sub (/^  /,"",name)
+    sub (/ heuristics: .*.$/,"",name)
+    if (!(name in branches))
+      {
+	names[nnames] = name
+	branches[name]=0
+	counts[name]=0
+	hits[name]=0
+	phits[name]=0
+	nnames++
+      }
+    branches[name]+=1
+  }
+
+/^  .* heuristics: .*. exec [0-9]* hit [0-9]* (.*.)$/ {
+    name=$0
+    sub (/^  /,"",name)
+    sub (/ heuristics: .*. exec [0-9]* hit [0-9]* (.*.)$/,"",name)
+    pred=$0
+    sub (/^  .* heuristics: /,"",pred)
+    sub (/. exec [0-9]* hit [0-9]* (.*.)$/,"",pred)
+    count=$0
+    sub (/^  .* heuristics: .*. exec /,"",count)
+    sub (/ hit [0-9]* (.*.)$/,"",count)
+    hit=$0
+    sub (/^  .* heuristics: .*. exec [0-9]* hit /,"",hit)
+    sub (/ (.*.)$/,"",hit)
+
+    if (int(pred) < 50.0)
+      {
+        hit = count"-"hit;
+      }
+    counts[name]=counts[name] "+" count
+    hits[name]=hits[name] "+" hit
+    phits[name]=phits[name] "+(("hit")<"count"/2)*("count"-("hit"))+(("hit")>="count"/2)*("hit")"
+
+    #BC crashes on long strings.  Irritating.
+    if (length(counts[name]) > 2000)
+      counts[name] = longeval(counts[name])
+    if (length(hits[name]) > 2000)
+      hits[name] = longeval(hits[name])
+    if (length(phits[name]) > 2000)
+      phits[name] = longeval(phits[name])
+  }
+END {
+  # Heuristics called combined predicts just everything.
+  maxcounts = longeval(counts["combined"])
+  maxbranches = branches["combined"]
+  max = names["combined"]
+  printf("HEURISTICS                 BRANCHES  (REL)  HITRATE              COVERAGE  (REL)\n")
+  for (i = 0; i < nnames ; i++)
+   {
+     name = names[i]
+     counts[name] = longeval(counts[name])
+     printf ("%-26s %8i %5.1f%% %6s%% / %6s%% %12s %5.1f%%\n",
+	     name,
+	     branches[name], branches[name] * 100 / maxbranches,
+	     longeval("("hits[name]") * 100 /(" counts[name]"-0.00001)"),
+	     longeval("("phits[name]") * 100 /(" counts[name]"-0.00001)"),
+	     counts[name], longeval(counts[name]" * 100 / ("maxcounts"-0.00001)"))
+   }
+}